Idea
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Hold out your hands and stretch your fingers. Have you ever wondered how our muscles enable us to perform precise and delicate works? Our muscles are composed of hierarchically organized structures, such as myofibrils, which is the smallest functional unit of muscles. Each myofibril relies on filaments, such as myosin and actin to produce nanoscale locomotion [B-1]. This structure of muscle inspired us. Hence, we selected molecular muscle as our project theme.
In previous studies, Scientists created a large, rigid rotaxane structure with DNA origami [B-3]. The ring of their structure could slide along the axle with 355 nm displacement. However, although the direction of ring's movement was guided by the axle, its exact position was not controllable.(Figure B1) Another research inspired us with the way to control the ring's movement. [B-4] (Figure B2) Researchers utilized toehold-mediated strand displacement to control the reaction kinetics of dynamic DNA devices. Based on these findings about the mechanically interlocked nanostructures [B-2], we designed a DNA origami structure which is analogous to myosin and actin. We modified and combined the ideas in these researches to create an unprecedented DNA origami, NanoMuscle.
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Figure B1. DNA origami mechanically interlocked nanostructures [B-3]
Figure B2. Toehold-mediated strand displacement [B-4]
NanoMuscle comprises two similar monomers. Each monomer has a ring and a base, connected by a 158nm-long axle. We designed a meticulous synthesis process (See Design) to ensure that pairs of monomers interlock in the correct orientation. Each interlocked monomer can slide along the axle of the other. With a specific sequence of ssDNA switch (See Design), the exact configuration (extended or contracted) of our NanoMuscle could be determined. (Figure B3)
Figure B3. Our DNA origami nanomuscle
Citation:
[B-1]
Bruns, Carson J., and J. Fraser Stoddart. "Rotaxane-based molecular muscles." Accounts of chemical research 47.7 (2014): 2186-2199.
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[B-2]
Chang, Jia-Cheng, et al. "Mechanically interlocked daisy-chain-like structures as multidimensional molecular muscles." Nature Chemistry 9.2 (2017): 128-134.
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[B-3]
List, Jonathan, et al. "Long-range movement of large mechanically interlocked DNA nanostructures." Nature communications 7 (2016).
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[B-4]
Machinek, Robert RF, et al. "Programmable energy landscapes for kinetic control of DNA strand displacement." Nature communications 5 (2014): 5324.